Motorcycle air suspension system

ABSTRACT

A suspension system for use with a motorcycle includes a device for producing a supply of pressurized air. The suspension system is operably disposed between a frame member and a swing arm of the motorcycle. The suspension system comprises a double-acting pneumatic cylinder.

This application is a continuation of U.S. patent application Ser. No.11/423,229, filed Jun. 9, 2006 now U.S. Pat. No. 7,559,396, which claimspriority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser.No. 60/689,454, filed Jun. 10, 2005, which is expressly incorporated byreference herein.

FIELD OF THE INVENTION

This invention generally relates to vehicle suspension systems. Moreparticularly, in an illustrated embodiment, the invention is directed toair suspension systems for motorcycle suspensions.

BACKGROUND OF THE INVENTION

In general terms, motorcycles typically include a main frame to whichthe engine is attached. One or more sub-frames or like elements can bemovably attached to the main frame, each of which can be adapted to holdone of the motorcycle wheels. The moving sub-frames may permit themotorcycle front and rear wheels to move relative to the main frame. Asuspension system may also be used to maintain the height of themotorcycle.

Traditionally, motorcycle suspension systems for street bikes haveincluded one or more springs (typically coil springs) and a hydraulicdamper unit applied to each of the front and rear wheel to provide thelift and dampening needed to suspend the vehicle and control movement ofthe wheels during compression and rebound of the wheels. Such a springand damper unit may be fastened between a swing arm and main frame inthe rear of the motorcycle to control the rear wheel assembly andassociated parts. Also, a spring and damper unit may be positionedinside a telescoping fork assembly to control the front wheel. Anotherform of a front fork, referred to as a “springer” fork, includes aspring suspension operating between two pairs of parallel fork membersin a well known manner.

Other suspension systems may use air in place of or in addition to thespring. These systems are often called air-ride suspension systems, andmay use rubber air bags as springs and may further be charged using acompressed air system. Compressed air may be varied to control the rideheight and the ride characteristics (i.e. firmness) of the motorcycle.However, the ride will inherently get firmer as the air pressureincreases in these systems.

SUMMARY OF THE INVENTION

The present invention relates to a suspension system havingdouble-acting air cylinders. In one illustrative embodiment, a controlmechanism allows the ride height to be adjusted independently of theride firmness. In such an embodiment, the operator may set the firmnessof the system and ride quality via two adjustments. A first adjustment,via a main regulator, can address the weight of the motorcycle, rider(s)and load. A second adjustment, via a bias regulator, can provide therebound control. The system is charged via an air compressor and may beapplied to either or both of the rear and front motorcycle suspension.

The present invention may also use a biasing pilot-operated high-reliefregulator. Such a bias regulator could automatically respond to,proportionally, the main regulator (pressure) setting; therefore, oncethe system is calibrated, only one adjustment is necessary. The biasregulator controls the dampening of the suspension action.

In another embodiment, the bias of the double-acting air cylinder is notadjustable, but rather is set to a pre-selected pressure, or isconfigured to utilize ambient air pressure.

Due to the compact size of the cylinders described herein, longersuspension strokes or travel is possible and allows travel of the fullstroke of the suspension. The system also allows the motorcycle frame tobe lowered to the ground.

Further, the system disclosed herein could be applied to other vehiclesor suspension systems, such as those found in autos and trailers.Accordingly, as referred to herein, the term “motorcycle” and the likemay be substituted by “vehicle”, “auto”, “trailer”, or any other usethat could incorporate the suspension system disclosed herein. Furtherfeatures and advantages of the invention will be readily apparent fromthe specification and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a partial motorcycle frame and swing arm assembly includingan air suspension device according to one embodiment of the invention;

FIG. 2 shows a diagram of an air suspension system according to oneembodiment of the invention;

FIG. 3 shows a diagram of an air suspension system according to a secondembodiment of the invention;

FIG. 4 shows a side view of a double-acting cylinder portion of theinvention;

FIG. 5 shows a top view of the double-acting cylinder of FIG. 4;

FIG. 6 shows a perspective view of the double-acting cylinder of FIG. 4;

FIG. 7 shows an end view of the double-acting cylinder of FIG. 4,

FIG. 8 shows a cross sectional view through lines 8-8 of FIG. 7;

FIG. 9 shows a cross sectional view through lines 9-9 of FIG. 7;

FIG. 10 shows a detail cross sectional view of area 10 of FIG. 9;

FIG. 11 shows a diagram of an air suspension system according to a thirdembodiment of the invention, wherein the pistons are in the extendedstate; and

FIG. 12 shows a diagram of the system of FIG. 11, wherein the pistonsare in the compressed state.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a well-known frame 20 and swing arm 22 arrangementreferred to as a SOFTTAIL® for a motorcycle. This type of frame andswing arm functions in a well known manner and a number of suspensionsystems have been proposed, designed and marketed which providesuspension functions to such a frame. Generally, the frame 20 includes apivoting swing arm or sub-frame 22, which moves in an arcuate fashionrelative to main frame 20 about pivot 24. A suspension component 26 ispivotably attached between a lower and rearward portion (i.e. a strut)28 of the main frame 20 and a lower and forward portion 30 of the rearwheel sub-frame 22. The suspension component 26 of the present inventionis described in more detail below.

In the illustrated embodiment, suspension component 26 is connected andoperates between main frame 20 and swing arm 22 and includes adouble-acting air cylinder in communication with a system 50. Arear-wheel embodiment of the system 50 is shown diagrammatically in FIG.2, and a front-and-rear-wheel embodiment is shown in FIG. 3. A battery52 provides electrical energy to electrical components of the system.The battery 52 may be the same battery that the motorcycle uses forignition, illumination and other electrical functions.

In one embodiment, a relay 54 is connected to the battery 52. Closingthe relay 54 permits electricity from the battery 52 to operate an airmotor or compressor 56. In one embodiment, the relay 54 is in the samecircuit as ignition switch 62; therefore, closing the switch closes therelay 54 and permits operation of the compressor 56. In operation,compressor 56 supplies high-pressure air to an air tank 58 through afilter 60. The filter 60 is provided to filter impurities, such asparticulate matter and oil.

A pressure switch 64 monitors the pressure in tank 58. The tank 58 maybe a separate tank or may be part of the frame, such that a frame membermay be used to contain pressurized air from the compressor 56. If thepressure is less than a predetermined amount, e.g. 150 pounds per squareinch (psi), the pressure switch 64 is closed, thereby energizing relay54. The switch 64 may therefore be configured to cause actuation of thecompressor 56 when the pressure drops a certain amount below thepredetermined desirable pressure. For example, switch 64 may betriggered at 12 psi below (i.e. 138 psi) the illustrative predetermined150 psi.

Illustratively, valve 66 is a solenoid interlock valve (i.e. a ClippardEE3TO-12 valve) that is connected to the ignition switch 62. Whenignition 62 is in the “off” position, valve 66 will not permit passageof pressurized air from the tank 58. This prevents damage that can bedone to the motorcycle by a bystander when the motorcycle is parked.Further, in the illustrative embodiment, turning switch 62 to the“lights on” position will permit compressor 56 to operate.

Toggle valve 68 is illustratively a manual air valve positioneddownstream from solenoid valve 66. When opened, toggle valve 68 permitsfull activation of the system 50. If the system 50 is pressurized andthe motorcycle ignition is on, the valve 68 may be opened by amotorcycle operator permitting pressurized air to pass through the valve68.

In the illustrated embodiment, pressurized air passing through theopened toggle valve 68 passes to the primary regulator 70. The primaryregulator 70, which is illustratively a relieving regulator, is used toproduce the desired amount of output pressure. The desired amount ofpressure may be preset by the motorcycle manufacturer or technician, butmay also be altered by the vehicle operator, who may select the amountof pressure delivered to suspension component 26 by changing the settingof primary regulator 70.

In one illustrated embodiment, air generated by primary regulator 70passes at the selected pressure through a one-way check valve 72, whichis illustratively a spring biased valve and valve seat. A pressurerelief valve 74 (or pressure dump valve) is coupled to the circuitbetween check valve 72 and wheel-side chamber 76 of the suspensioncomponent 26. Pressure relief valve 74 is a manually operated valvewhich permits the pressurized air to be vented from within thewheel-side chamber 76, an option that may be initiated by an operatorwanting a lower ride height.

The suspension component 26, which is illustratively a double-actingcylinder and piston arrangement, includes a housing 78 capable ofholding pressurized air. The illustrated housing defines a pair ofparallel air cylinders 80, 82. The use of parallel air cylinders such asthose described provides the advantage of greater resistance over asmaller stroke range. Disposed within the air cylinders 80, 82 are arespective pair of pistons 84, 86, which are sealed in the cylinders soas to prevent loss of air pressure. Such pistons are positioned toreciprocate within the cylinder bores. Each piston 84, 86 includes aconnecting rod 88, 90 for connecting the pistons to the swing arm 22 atpoint 30. When pressurized air enters wheel-side chamber 76, the pistons84, 86, are forced farther into the cylinders 80, 82, which causes thesuspension component 26 to shorten.

Looking at FIG. 1, one can see that by pressurizing chamber 76 andthereby shortening suspension component 26, sub-frame 22 will pivotabout pivot axis 24 in a direction indicated by arrow 25, and themotorcycle frame 20 will resultingly lift in a vertical direction. Inthe illustrated embodiment, the sub-frame 22 and frame 20 can beconfigured to move between a position that places the frame directly onthe ground and a position that raises frame 20 several inches off theground. In the raised position, the motorcycle may be ridden. Thelowered position may provide a resting or parked configuration for themotorcycle. Positions in between offer other low-profile riding options.

The pressurized air in chamber 76 provides the spring rate of the system50 and thus, the compression characteristics of the suspension and theride height of the motorcycle.

As can be seen in FIG. 2, housing 78 cooperates with pistons 84, 86 todefine a second set of chambers, i.e., frame-side chambers 92. In theillustrated embodiment, frame-side chambers 92 are at ambient pressurewhen the system is inactivated. However, when the system is activated,increased pressure in chambers 76 causes pistons 84, 86 to move in adirection indicated by arrows 91, thereby compressing the air inframe-side chambers 92.

In the embodiment illustrated in FIG. 2, pressurized air is supplied tothe frame-side chambers 92 at a secondary pressure to offset the primarypressure in chambers 76. Such a secondary air pressure is generated by abiasing regulator 94. One example of a biasing regulator 94 is a Type200 Precision Air Relay manufactured by ControlAir Inc.; moreinformation can be obtained at www.controlair.com. The biasing regulator94 is supplied with pressurized air from the toggle switch 68 and may bepreset by the system manufacturer, motorcycle manufacturer or in thealternative, adjusted for ride characteristics by the operator.

In the embodiment illustrated in FIG. 2, the secondary pressure outputby biasing regulator 94 is generated as a ratio of or is proportional tothe pressure from the primary regulator 70. As can be seen in FIG. 2,compressed air from primary regulator 70 is fed to biasing regulator 94,and biasing regulator 94 is configured to deliver the secondary pressureat a pressure relative to that of the input pressure from primaryregulator 70. Air supplied from the biasing regulator 94 is delivered tothe frame-side chamber 92 of suspension component 26 in part to offsetthe pressure in the wheel-side chamber. Such compressed air from thebiasing regulator 94 controls the rebound of the suspension component,and of the motorcycle as a whole.

As is further illustrated in FIG. 2, biasing regulator 94 provides acounterbalance to the air spring effect on an opposite side of thepiston as that of the main air suspension pressure. The biasingregulator maintains a ratio or proportional counterforce to the airspring unloaded setting, and thus, provides the rebound control in amanner which tracks any changes in the main air spring pressure. Airfunctions as an ideal spring due to the fact that the spring rate isprogressive during compression in contrast to most springs, which have alinear fixed compression rate.

FIG. 3 shows another embodiment, wherein an additional set of regulator,valve and suspension elements is provided to a front end of amotorcycle. As illustrated, a second air line downstream from togglevalve 68 feeds a second primary regulator 170. Pressurized air regulatedby second primary regulator 170 passes through one-way valve 172 andenters main chamber 176 of suspension unit 126. The secondary air supplyis supplied by bias regulator 94 to secondary bias air chambers 192 tooffset the air pressure in primary chambers 176. A venting pressurerelief valve 174 is coupled to the circuit between the check valve 172and main chamber 176. Such a pressure relief valve can relieve airpressure from chamber 176 in a fashion similar to that described abovefor pressure relief valve 74.

The device 126 used in the front suspension (such as a springer fork)may be a rotary actuator, or any type of double-acting cylinder.However, the invention contemplates any pneumatic device capable ofproviding the function of a double-acting cylinder/piston device, asshown in the figures and discussed in detail below.

Referring to FIGS. 2 and 3, one embodiment of a method of setting upand/or operating the system 50 includes turning on the system via toggleswitch 68, which charges the cylinders 76, 92 (and alternately 176 and192). When the flow is increased in primary regulator 70, an increasedair pressure is delivered to components 26, 126 until the motorcyclerises. This setting also controls the firmness of the suspension. Then,bias regulator 94 is adjusted to set the dampening of the system. If ata later point, the primary regulator flow is adjusted, such as to lowerthe ride height, the bias regulator 94 will automatically follow theadjustment to the primary regulator. The bias regulator 94 can also beadjusted to change or modify the rebound effect.

While the rider is on the motorcycle, the motorcycle ride height can bereduced or lowered by pressing pressure relief valve(s) 74, 174. Theride height will remain at this new changed setting until the rider getsoff the motorcycle.

In the embodiment illustrated in FIG. 2, system 50 has a “memory” of thedesired ride height. A rider will often desire to lower the height ofhis/her motorcycle, i.e. while riding the motorcycle and desiring alower profile, or when the motorcycle is parked and it is desired tolower the frame to the ground. When the ignition key is later turned tothe “on” position, compressed air that is stored in either an externaltank or in tank 58 is delivered to system 50, and the ride firmness orquality that was previously set by the rider is recovered. In thealternative, the rider can adjust the primary regulator 70 to a newsetting, resulting in a new ride firmness.

One advantage of the present invention is the ability of suspensioncomponent 26 to have a greater stroke length, extending beyond twoinches and to as much as 2.5 inches. This allows for greater fluctuationin the height of the rear of the motorcycle, and permits a greater rangeof use for the suspension component.

As a safety feature, as can be seen in FIG. 1, a stop 21 isillustratively added to prevent the accidental lowering of themotorcycle ride height to an unsafe level during operation. Such a stop21 can be as simple as a pin inserted through an aperture in frame 20,the pin blocking further pivoting movement of sub-frame 22. The pincould be spring-loaded so that it automatically moves into the lockingposition once the motorcycle is raised above the lowest, parked height.

FIGS. 4-7 show various views of the exterior of suspension component 26.The suspension component 26 illustratively comprises a single housing 78having parallel rods 88, 90 disposed therein. Rods 88, 90 are connectedinside the housing 78 to pistons (84 and 86 in FIGS. 2 and 9). Rods 88,90 connect to the swing arm 22 at point 30 (shown in FIG. 1). As can beseen in FIGS. 7-10, housing 78 is closed at one end by main chamber cap96 which closes off wheel-side chambers 76. Housing 78 is closed at anopposite end by secondary chamber cap 98 (shown in FIGS. 8 and 9), whichcloses off the secondary or bias chambers 92 (shown in FIG. 2). Thesecondary chamber cap 98 includes a pair of extensions 100, 102 forconnecting the unit 26 to the frame 20 at point 28 (of FIG. 1). A firstair fitting 104 is provided for attaching an air line to cap 96 forsupplying main air supply to wheel-side chambers 76 (of FIG. 2). Thecross-sectional view of suspension component 26 in FIG. 8 shows aprimary air bore 108 formed in cap 96 for supplying the compressed airfrom primary regulator 70 that is directed through first fitting 104.Channel 109, shown in FIGS. 8-10, permits distribution and equalizationof air pressure between main chambers 76.

In the disclosed embodiment, rod ends 89, 91 of rods 88, 90(respectively) and extensions 100, 102 include a self-lubricatingbearing material that permits extended function. Furthermore, thetolerances for rod ends 89, 91 and extensions 100, 102 are such that thesuspension component 26 may be installed on a variety of motorcycles andeven on frames having slight offsets or imperfections. For example, inan illustrative embodiment, rod ends 89, 91 and extensions 100, 102 eachhave a 0.850″ width and are configured to ride on a standard 1″ wideshoulder bolt. Therefore, the swing arm 22 may be out of alignment withthe main frame 20 by as much as 0.300″ without having the suspensioncomponent affected by the misalignment. Such tolerances permitattachment of the suspension component 26 to varying widths andconstructions for motorcycle frames.

A second fitting 106 is also shown in FIG. 8. Second fitting 106 canillustratively be an air fitting for attaching an air line to cap 96, ora check valve (illustrated in FIGS. 11 and 12) that permits the entry ofair into chambers 92, but prevents the exit of air from chambers 92, asdiscussed further herein. Air bore 110 is also provided for deliveringair from second fitting 106 to chambers 92.

In the air fitting embodiment (shown schematically in FIG. 2), secondfitting 106 provides a port into chambers 92, through which bias air issupplied to bias chambers 92. In such an embodiment, biasing regulator94 directs compressed air through second fitting 106 and through airbore 110 in order to pressurize chambers 92.

In the alternative, a check valve system 150, shown in FIGS. 11 and 12,utilizes a second fitting 106 that is a check valve, thereby permittingambient air to function as the biasing element. In the check valvesystem 150, as pistons 84, 86 approach the deactivated state shown inFIG. 11, wherein pistons 84, 86 are near or adjacent to chamber cap 96,check valve 106 permits ambient air to enter chambers 92. For example,during the initial installation of the check valve, the initialsuspension travel (extension) will suction air through the check valveinto chambers 92, and the check valve will seat. This air is now trappedand will act as an air spring.

In such a check valve system 150, a biasing regulator is not neededbecause the bias results from this trapped (ambient) air. Uponactivation of system 150, the trapped air present in chambers 92 iscompressed as the pistons 84, 86 move away from chamber cap 96. Theopposing air spring force dampens the retract motion of the pistons,thus creating rebound control when the motorcycle suspension encountersbumps. Accordingly, the system is greatly simplified because a simplebiasing system is provided without the use of a biasing regulator.

More particularly, when pistons 84, 86 are fully extended in theposition shown in FIG. 11, and therefore chambers 92 are at theirgreatest volume, the pressure in chambers 92 may otherwise be broughtbelow ambient pressure (either due to the fact that it is the initialextension of the pistons, or because some pressure was lost). However,check valve 106 allows air to be pulled inside chambers 92, andeventually used as the “bias” when the system is activated. Uponactivation of system 150, compressed air is directed into chambers 76,forcing pistons 84, 86 to move toward chamber cap 98 and meanwhilecompress the air in chambers 92. A typical active state for the systemmay be when the pistons are located somewhere between the positionsshown in FIGS. 11 and 12.

In yet another alternative embodiment, chambers 92 may bepre-pressurized to a pre-selected level prior to delivery to theconsumer. A desirable pre-selected pressurization level has beendetermined to be approximately three pounds-per-square-inch (while inthe deactivated position shown in FIG. 11), but any pressure above zeropsi and below 10 psi is contemplated to be within the scope of theinvention.

FIGS. 9 and 10 illustrate that piston 84 is connected to rod 88 anddisposed to reciprocate in cylinder bore 80. Likewise, piston 86 isconnected to rod 90 and disposed to reciprocate in cylinder bore 82.

Systems 50 and 150 illustratively use small diameter tubing, which actas a flow control and provide some dampening to the system. As disclosedabove, the systems 50, 150 may also store compressed air for operationof components in the system. Such stored compressed air would permit thesystem to be activated as soon as it is turned on.

The system may also have an interlock safety feature to the ignitionsystem, wherein a toggle switch is defeated unless the control system isenergized. The system can also return automatically to pre-set pressuresettings. Therefore, the operator does not have to adjust the systemevery time the vehicle is ridden. The system would automatically resetthe height when the rider removes his or her body weight from the seat.

While the disclosure is susceptible to various modifications andalternative forms, specific exemplary embodiments thereof have beenshown by way of example in the drawings and have herein been describedin detail. It should be understood, however, that there is no intent tolimit the disclosure to the particular embodiments disclosed, but on thecontrary, the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the disclosure asdefined by the appended claims.

1. A motorcycle frame comprising a main frame a swing arm pivotablycoupled to the main frame and configured to support a motorcycle wheelthereon, and a suspension component coupled to the main frame and theswing arm and configured to affect pivotable movement between the mainframe and the swing arm, wherein the suspension component comprises abiasing regulator, and wherein the suspension component furthercomprises a single body pneumatically coupled to the biasing regulator,the single body housing two double-acting pneumatic cylinders therein.2. The motorcycle frame of claim 1, wherein the double-acting pneumaticcylinders are in pneumatic communication with each other.
 3. Themotorcycle frame of claim 2, wherein the double-acting pneumaticcylinders communicate via an internal port disposed inside the singlebody.
 4. The motorcycle frame of claim 1, wherein the double-actingpneumatic cylinders are arranged in parallel.
 5. The motorcycle frame ofclaim 1, wherein each double-acting pneumatic cylinder comprises apiston positioned within an elongated cylinder, the piston defining afirst chamber at one end of the cylinder and a second chamber at theopposite end of the cylinder.
 6. The motorcycle frame of claim 5,wherein the first chamber is in communication with a compressed airsource.
 7. The motorcycle frame of claim 5, wherein the second chamberis in communication with ambient air.
 8. The motorcycle frame of claim7, further comprising a check valve coupled to the second chamber, thecheck valve permitting the intake of ambient air into the secondchamber.
 9. The motorcycle frame of claim 5, wherein the second chamberis pre-pressurized to a predetermined pressure.
 10. The motorcycle frameof claim 5, wherein the second chamber is in communication with thebiasing regulator.
 11. The motorcycle frame of claim 1, wherein thebiasing regulator is adjustable by a user.
 12. The motorcycle frame ofclaim 1, wherein the biasing regulator is set at a predeterminedposition by a manufacturer.
 13. The motorcycle frame of claim 1, whereinthe biasing regulator maintains the pneumatic pressure of a secondchamber as a ratio of the pneumatic pressure of the first chamber.
 14. Amotorcycle frame comprising a main frame a swing arm pivotably coupledto the main frame and configured to support a motorcycle wheel thereon,and a suspension system configured to trap air in a rebound controlchamber and configured to utilize the trapped air in the rebound controlchamber to provide suspension rebound control, wherein the suspensionsystem further comprises a housing having two double-acting pneumaticcylinders for affecting movement between the main frame and the swingarm.
 15. The motorcycle frame of claim 14, wherein the double-actingpneumatic cylinders are in pneumatic communication with each other. 16.The motorcycle frame of claim 15, wherein the double-acting pneumaticcylinders communicate via an internal port disposed inside the singlebody.
 17. The motorcycle frame of claim 14, wherein the double-actingpneumatic cylinders are arranged in parallel.
 18. The motorcycle frameof claim 14, wherein each double-acting pneumatic cylinder comprises apiston positioned within an elongated cylinder, the piston defining afirst chamber at one end of the cylinder and a second chamber at theopposite end of the cylinder.
 19. The motorcycle frame of claim 18,wherein the first chamber is in communication with a compressed airsource.
 20. The motorcycle frame of claim 18, wherein the second chamberis in communication with ambient air.
 21. The motorcycle frame of claim20, further comprising a check valve coupled to the second chamber, thecheck valve permitting the intake of ambient air into the secondchamber.
 22. The motorcycle frame of claim 20, wherein the secondchamber is pre-pressurized to a predetermined pressure.
 23. Themotorcycle frame of claim 20, wherein the second chamber is incommunication with a biasing regulator.
 24. The motorcycle frame ofclaim 23, wherein the biasing regulator maintains the pneumatic pressureof the second chamber as a ratio of the pneumatic pressure of the firstchamber.
 25. The motorcycle frame of claim 23, wherein the biasingregulator is adjustable.
 26. The motorcycle frame of claim 20, whereinthe first and second chamber are not in pneumatic communication witheach other.
 27. The motorcycle frame of claim 14, wherein the suspensionsystem comprises a biasing regulator.